1 /*
2  * Copyright (C) 2008 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package com.android.launcher3;
18 
19 import android.content.Context;
20 import android.graphics.Rect;
21 
22 import com.android.launcher3.accessibility.DragViewStateAnnouncer;
23 import com.android.launcher3.config.FeatureFlags;
24 import com.android.launcher3.dragndrop.DragOptions;
25 import com.android.launcher3.dragndrop.DragView;
26 import com.android.launcher3.dragndrop.DraggableView;
27 import com.android.launcher3.folder.FolderNameProvider;
28 import com.android.launcher3.logging.InstanceId;
29 import com.android.launcher3.logging.InstanceIdSequence;
30 import com.android.launcher3.model.data.ItemInfo;
31 import com.android.launcher3.util.Executors;
32 
33 /**
34  * Interface defining an object that can receive a drag.
35  *
36  */
37 public interface DropTarget {
38 
39     class DragObject {
40         public int x = -1;
41         public int y = -1;
42 
43         /** X offset from the upper-left corner of the cell to where we touched.  */
44         public int xOffset = -1;
45 
46         /** Y offset from the upper-left corner of the cell to where we touched.  */
47         public int yOffset = -1;
48 
49         /** This indicates whether a drag is in final stages, either drop or cancel. It
50          * differentiates onDragExit, since this is called when the drag is ending, above
51          * the current drag target, or when the drag moves off the current drag object.
52          */
53         public boolean dragComplete = false;
54 
55         /** The view that moves around while you drag.  */
56         public DragView dragView = null;
57 
58         /** The data associated with the object, after item is dropped. */
59         public ItemInfo dragInfo = null;
60 
61         /** The data associated with the object  being dragged */
62         public ItemInfo originalDragInfo = null;
63 
64         /** Where the drag originated */
65         public DragSource dragSource = null;
66 
67         /** Indicates that the drag operation was cancelled */
68         public boolean cancelled = false;
69 
70         /** Defers removing the DragView from the DragLayer until after the drop animation. */
71         public boolean deferDragViewCleanupPostAnimation = true;
72 
73         public DragViewStateAnnouncer stateAnnouncer;
74 
75         public FolderNameProvider folderNameProvider;
76 
77         /** The source view (ie. icon, widget etc.) that is being dragged and which the
78          * DragView represents. May be an actual View class or a virtual stand-in */
79         public DraggableView originalView = null;
80 
81         /** Used for matching DROP event with its corresponding DRAG event on the server side. */
82         public final InstanceId logInstanceId =
83                 new InstanceIdSequence(1 << 20 /*InstanceId.INSTANCE_ID_MAX*/)
84                     .newInstanceId();
85 
DragObject(Context context)86         public DragObject(Context context) {
87             if (FeatureFlags.FOLDER_NAME_SUGGEST.get()) {
88                 Executors.MODEL_EXECUTOR.post(() -> {
89                     folderNameProvider = FolderNameProvider.newInstance(context);
90                 });
91             }
92         }
93 
94         /**
95          * This is used to compute the visual center of the dragView. This point is then
96          * used to visualize drop locations and determine where to drop an item. The idea is that
97          * the visual center represents the user's interpretation of where the item is, and hence
98          * is the appropriate point to use when determining drop location.
99          */
getVisualCenter(float[] recycle)100         public final float[] getVisualCenter(float[] recycle) {
101             final float res[] = (recycle == null) ? new float[2] : recycle;
102             Rect dragRegion = dragView.getDragRegion();
103 
104             // These represent the visual top and left of drag view if a dragRect was provided.
105             // If a dragRect was not provided, then they correspond to the actual view left and
106             // top, as the dragRect is in that case taken to be the entire dragView.
107             int left = x - xOffset - dragRegion.left;
108             int top = y - yOffset - dragRegion.top;
109 
110             // In order to find the visual center, we shift by half the dragRect
111             res[0] = left + dragRegion.width() / 2;
112             res[1] = top + dragRegion.height() / 2;
113 
114             return res;
115         }
116 
117 
118         /**
119          * This is used to determine if an object is dropped at a different location than it was
120          * dragged from
121          */
isMoved()122         public boolean isMoved() {
123             return dragInfo.cellX != originalDragInfo.cellX
124                     || dragInfo.cellY != originalDragInfo.cellY
125                     || dragInfo.screenId != originalDragInfo.screenId
126                     || dragInfo.container != originalDragInfo.container;
127         }
128     }
129 
130     /**
131      * Used to temporarily disable certain drop targets
132      *
133      * @return boolean specifying whether this drop target is currently enabled
134      */
isDropEnabled()135     boolean isDropEnabled();
136 
137     /**
138      * Handle an object being dropped on the DropTarget.
139      *
140      * This will be called only if this target previously returned true for {@link #acceptDrop}. It
141      * is the responsibility of this target to exit out of the spring loaded mode (either
142      * immediately or after any pending animations).
143      *
144      * If the drop was cancelled for some reason, onDrop will never get called, the UI will
145      * automatically exit out of this mode.
146      */
onDrop(DragObject dragObject, DragOptions options)147     void onDrop(DragObject dragObject, DragOptions options);
148 
onDragEnter(DragObject dragObject)149     void onDragEnter(DragObject dragObject);
150 
onDragOver(DragObject dragObject)151     void onDragOver(DragObject dragObject);
152 
onDragExit(DragObject dragObject)153     void onDragExit(DragObject dragObject);
154 
155     /**
156      * Check if a drop action can occur at, or near, the requested location.
157      * This will be called just before onDrop.
158      * @return True if the drop will be accepted, false otherwise.
159      */
acceptDrop(DragObject dragObject)160     boolean acceptDrop(DragObject dragObject);
161 
prepareAccessibilityDrop()162     void prepareAccessibilityDrop();
163 
164     // These methods are implemented in Views
getHitRectRelativeToDragLayer(Rect outRect)165     void getHitRectRelativeToDragLayer(Rect outRect);
166 }
167